Abstract

Cnidaria include the most venomous animals of the world. Among Cnidaria, Scyphozoa (true jellyfish) are ubiquitous, abundant, and often come into accidental contact with humans and, therefore, represent a threat for public health and safety. The venom of Scyphozoa is a complex mixture of bioactive substances—including thermolabile enzymes such as phospholipases, metalloproteinases, and, possibly, pore-forming proteins—and is only partially characterized. Scyphozoan stings may lead to local and systemic reactions via toxic and immunological mechanisms; some of these reactions may represent a medical emergency. However, the adoption of safe and efficacious first aid measures for jellyfish stings is hampered by the diffusion of folk remedies, anecdotal reports, and lack of consensus in the scientific literature. Species-specific differences may hinder the identification of treatments that work for all stings. However, rinsing the sting site with vinegar (5% acetic acid) and the application of heat (hot pack/immersion in hot water) or lidocaine appear to be substantiated by evidence. Controlled clinical trials or reliable models of envenomation are warranted to confirm the efficacy and safety of these approaches and identify possible species-specific exceptions. Knowledge of the precise composition of Scyphozoa venom may open the way to molecule-oriented therapies in the future.

Highlights

  • Cnidarians (Hatschek, 1888) are one of the oldest phyla and have existed since at least the Cambrian [1]

  • These findings indicate that matrix metalloproteases and phospholipase A2 (PLA2) and possibly other PLs can be regarded as novel therapeutic targets in scyphozoan envenomation

  • We envision that first aid protocols for scyphozoan stings should:

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Summary

Introduction

Cnidarians (Hatschek, 1888) are one of the oldest phyla and have existed since at least the Cambrian [1]. Following mechanical–chemical stimulation, the tubule is quickly everted, injecting into the teguments of the prey or predator the venomous substances This event is called discharge and is known as one of the fastest processes in the animal kingdom [8,11,12]. Phase contrast microphotographs of (a) undischarged and (b) discharged holotrichous-isorhiza nematocysts isolated from Pelagia noctiluca (Cnidaria: Scyphozoa) oral arms. Being present in both coastal and open waters at different depths, cnidarians often come into accidental contact with humans, interfering with human activities and having a considerable impact on public safety, health, and economy. The aim of the present work is to give an overview of the first aid measures for scyphozoan stings based on scientific information, with special emphasis on the mechanistic activity of specific venom components

Components of Scyphozoan Venom and Their Activity
Phospholipase A2
Metalloproteases
Serine Proteases
Other Proteases
Serine Protease Inhibitors
Hyaluronidases
Deoxyribonucleases
L-Amino Acid Oxidases
C-Type Lectins
Neurotoxins and Other Ion Channel Blockers
Pore-Forming Toxins
2.10. Cysteine-Rich Secretory Proteins
2.11. Other Venom Components of a Protein Nature
Reactions to Scyphozoan Stings
Local Reactions to Scyphozoan Stings
Systemic Reactions
First Aid Measures for Scyphozoan Stings
Prevention of Further Discharge of Nematocysts After a Sting
Rinsing with Seawater
Rinsing with Vinegar or Acetic Acid
Rinsing with Urine or Solutions Containing Urea or Ammonia
Additional Rinsing Solutions
Bicarbonate and Baking Soda Slurry
Limiting the Action of the Venom in Terms of Pain and Tissue Damage
Heat or Cold Packs
Lidocaine and Local Anesthetics
Further Considerations and Hints for Future Studies
Findings
Conclusions

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